Alcohol alkoxylates and derivatives thereof, such as alkyl ethoxy sulfates (or alcohol ethoxy sulfates (AES)), find utility in a wide variety of applications, e.g., surfactants for use in detergents. The general reaction of alcohols and ethylene oxide to form ethoxylated alcohols or ethylene oxide adducts, has long been known and practiced on a commercial scale. For example, these ethylene oxide adducts have been used as detergents and cleaning agents, domestic and industrial laundry detergents, detergent builders, polishes, sanitizers, and dry cleaning materials.
Much literature is available in the general area of alkoxylation of alcohols. Many references are also available relating to the catalytic ability of various materials, and the mechanism and kinetics of these reactions. Generally, an alkoxylation reaction involving a compound having an active hydrogen, e.g., alcohol, is conducted by the condensation of an alkylene oxide using a suitable catalyst. Both basic, e.g., KOH, and acidic catalysts, e.g., BF3, are known for use in alkoxylating alcohols. Alkoxylation of alcohols, however, produces a distribution of various adducts (homologs), not a pure compound. For example, in surfactant applications, an adduct with too few ethylene oxide molecules may not be effective because of poor solubility, while an adduct with too many ethylene oxide molecules may likewise be undesirable because surface tension reduction per unit mass decreases drastically with increasing molecular weight. Thus, there is a need for alkoxylates with a narrow distribution in the selected mole adduct range for the particular use of the material.
Known acid catalyzed reactions, such as BF3, produce narrow range (peaked) alcohol alkoxylates, but these catalysts produce undesirable side products that must be separated and removed prior to use. Base catalysts normally do not produce the level of by-products which acidic catalysts do, but provide a much broader distribution of alkoxylation adducts. Therefore, it would be desirable to provide alcohol alkoxylates with a narrow distribution of the preferred mole adducts, which are produced by a catalyst system that does not produce undesirable by-products.
The use of a catalyst composition obtained by mixing a zinc salt of organosulfonic acid in one or more liquids selected from water, lower alcohols, higher alcohols, glycol ethers and aromatic solvents, where the ratio of organosulfonic acid/zinc oxide=5/1 to 1/10 (mole ratio), is known. However, the use of zinc organosulfonic acid as a catalyst involves another separate process to make the zinc salt of the organosulfonic acid.